Author Topic: tuning problem  (Read 3101 times)

Offline Z28 c10

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tuning problem
« on: May 26, 2006, 09:32:00 PM »
Alright guys, I' m about ready to stick a stick of TNT under my '81 and distribute parts to everyone I can in the area. The problem, on my 355, I had tuned the carb and timing to where the motor would run good, somewhat, great response and driveability, only thing is it would only run that way in the morning. During the afternoon and evening, it would miss and stutter. Last night I finally popped the hood and found a hole rubbed into the metal line going to the vacuum modulater on the trans. So after fixing the vac leak the truck runs terrible AT ALL TIMES! I've tried changing the metering rods and springs on the carb ( 1406 E-brok 650 ) and there hasn't been any change. I put a timing light on, and it's dead on time. No matter what I've done short of rejetting, nothing seems to do the trick, she' still surging at part throttle and just before shifting it breaks up ( around 3500-4000 RPM ) Any help would be GREATLY appreciated.

 JayTater

 Z28 C10


Offline DnStClr

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Re: tuning problem
« Reply #1 on: May 26, 2006, 09:20:00 PM »
Any chance that you have a plug wire breaking down when it gets warm?

Don
87 Chevy Silverado

Offline Z28 c10

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Re: tuning problem
« Reply #2 on: May 27, 2006, 04:16:00 PM »
No, they're brand new Accel 300+ wires. I put a vac gauge on the advance and on the vac module on the trans and no leaks there either. I'm going nuttin futs on this one.

 JayTater

 Z28 C10


Offline 1976Scottsdale

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Re: tuning problem
« Reply #3 on: May 27, 2006, 06:50:00 PM »
Have you re-set the valves yet, too tight perhaps?  Mine had a similar problem and the valves were a bit tight.  Also, not to insult or anything the like, on small blocks, people will often place the number 1 plug wire directly after the plugs for the battery and ground, if yours is this way, it will run okay, but if it is, try moving one terrminal clockwise.  Also, take the carb and set your screws to 1 1/4 turns out on each and then go from there.  You may also need to adjust the choke... or the screw for the fast idle.


Offline 123 pugsy

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Re: tuning problem
« Reply #4 on: May 27, 2006, 09:04:00 PM »
It appears that you adjusted your carb to run well with a vacuum leak.As 76' said ,you probably gotta look at all your carb settings.If it ran good in the morning when the choke was on,could the choke still be on after the engine is warmed up causing it to run poorly??

Pugsy
76 C10 LWB
TPI 350

Offline Z28 c10

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Re: tuning problem
« Reply #5 on: May 28, 2006, 04:23:00 AM »
yeah, I had it running pretty decent before discovering the vacuum leak as said before. The choke is actually disconnected at this time because theres really no need for it here in Florida during the summer. The only thing I can think of is that I jetted the carb down, i mean WAY down before finding the leak, so I'm going to jet'er back up later on this morning and see where that gets me. I'll get back on after she's done and let ya'll know what happens.

 JayTater

 Z28 C10